Earth appears to be unique and inhabited by living creatures, but the building blocks required for life to bloom are actually quite common, according to new research.
"Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth", said Siyi Xu, an an assistant …

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Give it a couple of million years

Re: Give it a couple of million years

"And there'll be a human output in every corner of the galaxy." No, unless 'human' is a generic term for tool and language using sentient creatures rather than homo sapiens. Perhaps we shouldn't be speciest.

Interstellar space is like a quarantine system. Unless there is physics we don't know about. A generation ship is theoretically possible. No evidence that cryogenics does anything other than kill mammals. Some sort of hibernation with a short awake period every few months might be plausible.

SF needs starships. It doesn't mean they have to exist in the real universe, though it would be interesting if they did.

Re: Give it a couple of million years

This article seems pretty dated, as more recent research suggests that most of the variance between different subgroups of humans is due to mixing with other human species like Neanderthals, Denisovans. The timeframes mentioned in the article are nowhere near enough to "evolve" in any capacity. The evolution happened over much larger timeframes and across the entire homo family tree.

Re: @HampsterNet - Epigenetics

Epigenetics is not evolution nor is it mutation. It is the expression of "suppressed" genes due to changed environmental factors. The genes are already there by normal inheritance but another set or even the same set are just expressed differently due to need; think lung size when changing from a low altitude to a high altitude environment and vice versa.

Native High Andes dwellers have larger lungs than the norm, move them to a coastal environment and in three generations their lungs are the same as the norm. Move them back up and three generations later they have large lungs again.

Re: Give it a couple of million years

"Epigenetics isn't evolution"

Epigenics and evolution are closely intertwined. Evolution and mutation happen all the time - in fact the pool of mutations and evolutionary tweaks maximises during unstressed conditions (such as our species is experiencing now). This is why our species is evolving faster now than at any point in its history - but that's happening in all directions at once with no clear advantage to any particular change.

It's only when stressful conditions or new niches come along that some of those will prove advantageous to the individuals who have them BUT they're only useful going forward if those genes are passed along AND the descendants stay exposed to that condition in order to further enhance the selection.

Environmental stress points act as a filter, removing the unhelpful evolutionary changes (in the case of widespread environmental change) or splitting development into lines suited to a particular environment vs a more general one."Survival of the fittest" was never the best way of expressing that because in the vast majority of changes it's the latter, not the former - but then those specialisations frequently run into dead ends and extinction when the "particular environment" disappears (so in the long term, the generalist survives whilst the specialist doesn't)

Re: Give it a couple of million years

"Our genetic makeup is pretty much the same"

Exactly my point. Don't forget, people, that the person I was replying to said that humans in 10,000 wouldn't look anything like us now. While being taller or shorter, or having a bigger or smaller brain, etc, may well be significant changes, they are a long way short of that. I said we haven't changed that much - and we haven't; we would easily recognise a human of 10,000 years ago as, well, a human.

Re: Give it a couple of million years

We are very different from 10000 years ago. We know a female from a village in Australia could run faster than usain bolt while "Jogging" on a beach. (from the stride distance of preserved foot prints)

Since then we have gone backwards in terms of strength, fitness and our ability to process food stuffs, illnesses even certain weather because we have clothes and shoes and medicine to help. Which in turn has let us survive as a weaker form, live longer etc.

We were also much much shorter, a few hundred years ago, never mind 10000. Just look at Japan over the last 50 years to see how changes in diet and lifestyle can impact height. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5811819/

Today we have AI, robots and a massive obesity problem because our diets and lifestyle are very different. You think in 10000 years it won't have changed us again.

@ Avatar of They

Our ability to process foods is certainly not going backwards, you find just about everything you can wish for in supermarkets. Medicine is getting better all the time and cancer treatments are improving, although not by leaps and bounds.

Finally, we do not have AI. We have continually improving statistical analysis machines that work on very specific data sets, but that is not Artificial Intelligence.

We certainly do have an obesity problem, but that is exactly because we know how to process the shit out of food. And we're all lazy as fuck, at least in the traditionally-named "developed" countries. Maybe if we didn't have 150 different types of chips, things would be a bit more under control in the belt area.

Re: @ Avatar of They

Re: @ Avatar of They

" cancer treatments are improving, although not by leaps and bounds."

Bear in mind that the primary reason more people are GETTING cancer isn't down to environmental factors for the most part(*). It's because more people are living long enough to GET cancer in the first place (or have small ones progress to the point where they're the cause of death rather than something that was present at death but not the cause.

(In the same vein, people throw out the stat that the rise of the rate of cancers in domestic dogs and cats in the 1970s directly tracks the increase in the rate of use of canned/bagged petfood - but neglect to mention that it also directly tracks the increasing lifespan of those pets in the same period.)

(*) There are definitely clusters attributable to environmental factors but overall it's age-related - and high levels of ionising radiation exposure doesn't usually CAUSE cancers, but by suppressing/damaging the immune system it frequently allows existing ones to grow faster than they usually would because the body's not killing off the mutated cells.

Re: @ Avatar of They

Right. My first cat (owner), a female Seal-Point Siamese, lived until she was 23. My second, a Burmese, lived until she was 27. She was hanging on my screen door yowling her head off, didn't know she was already 11 until we had the vet look at her. My Mom's, a 28# Maine Coon-Cat, lived until he was 20 even despite the fact that he had diabetes.

We are properly trained cat slaves around here.

[Hell, I just had a 18# male mixed breed cat try to come home with me. Strolled right on out and surrendered to me (rolled up on his back exposing his neck and stomach) on the spot. A 4.5 month old kitten just strolled on in one day, three months ago, and took up residence. Never a problem having a cat, or three, around. ]

Re: Give it a couple of million years

10,000 years of corporations getting rich by selling us crap that makes them money and us sick? Icon? I'm checking for some cash to go and get breakfast ... a bowl of granola with a extra dash of Roundup please, and some milk with bovine somatotropin too while I read the FT and see how my shares are doing - going up again, wonderful!

Re: Give it a couple of million years

Avatar of They - it seems you don't understand natural selection at all. You are describing the influence of environmental factors on a static genome. H sapiens sapiens has been around for a couple of hundred thousand years with very little variation. Things like height are very much diet and exercise related; thus hunter gatherers tend to be taller than subsistence farmers. But the average height and weight of Britons has changed in the last 70 years due to food availability, showing this is short term environment change.

In fact we are little different from Neanderthals.

As another example, dogs started to be domesticated roughly 17000 years ago. Huskies split off from dogs about 8000 years ago. Because of the flexibility of the dog genome, we have produced numerous breeds - but cross breeding rapidly causes reversion to Mk. 1 dog. And most people do not even realise that huskies are a different race of dogs. This despite intensive breeding.

Re: Give it a couple of million years

Re: Give it a couple of million years

Just need 1G acceleration.

At that everything becomes very travelable indeed with time dilation making the journey appear vastly shorter from the perspective of the traveller. With 1G you can get to other galaxies in a single lifetime of the traveller, even if millions of years pass back on earth. You never actually reach the speed of light, despite constantly accelerating at 1g for half the journey and decelerating for the other half. The energy requirements are staggering tho, even if you can find a way of pushing off without lobbing stuff out the back.

Re: Just need 1G acceleration.

Not possible for very long. A variation of the rocket equation applies to carrying the fuel (even antimatter), the longer the thrust, the more fuel and thus the more fuel needed for same thrust due to higher mass.

Forget solar power (light or wind) except to accelerate to edge the Kuiper belt. The Oort Cloud is about a thousand times further than the Kuiper belt. Any likely nearby stars are 10x to 100x further. Space is really really big.

Secondly, you need more thrust to maintain 1G as you get faster.

It's probably not possible to maintain 1G even 1/2 way to the nearest star. Basic physics & mathematics says no.

Re: Just need 1G acceleration.

Many ways around this have been proposed, Light sails + lasers/masers work, for longer distances one option is to relay them making interstellar highways, the only obstacle to that is local power generation.

Some promising hints of massless thrusters are appearing with the EM drive and alike. Then there is just a simple Photon drive which is already in existence (just shoot a laser out the back works, but you need a lot of light to make 1g on anything).

Relying on chucking stuff out the back is never going to get man much beyond mars

Re: Give it a couple of million years

If you could accelerate at 1g for one year, you would reach the speed of light. Decelerate at 1g for a year, and you are done. Assuming you don't hit anything - since you are traveling at the speed of light you have no way to maneuver around anything - by the time you could sense something you are already there.

Re: unless 'human' is a generic term

What Crisp said was that there will be a human output in every corner of the galaxy. In other words, someone is going to poop in the corners of the galaxy. Going to take a good chunk of those couple of million years to figure out where the corners are, though...

Re: Alternative life forms

"The universe is probably teeming with life but in forms that we do not recognize or understand or are capable of understanding from a chemical/physical point of view."

On the other hand every time we've assumed our conditions are "special", we've been proven wrong.

Water and carbon are some of the most common items out there in the universe. Most other possible chemistries are difficult without extreme (from our point of view) temperatures and would be heavily poisoned by the presence of either of the above. That's not to say they're impossible, but carbon-based life is the most likely form. It could be anaerobic or aerobic but it's a fairly safe bet to assume that within a few billion years of anaerobic life evolving on any planet with access to sunlight some species will develop a way of harnessing the light energy and splitting water in the process, generating oxygen in the process (which will kill off virtually everything else, as happened on earth)

Seeing an oxygen signature in any planetary atmosphere is a telltale indication of life "as we know it" - the "plants" may not be green (that's an artifact of the light frequencies available to the first chloroplasts trying to get light after the blue-green and red algae had hoovered up most of it), but it would be carbon-based, water-splitting and light-eating.

Carbon-based anaerobic life would virtually always inevitably give way to aerobic life due to the evolution of oxygen-generators. The harvesting of available "free" energy (much easier to deal with than thermal energy) makes this almost certain over evolutionay time periods. Even if the results are random when you throw the dice, eventually you will throw 5 sixes (Yahtzee!) 4 times in a row. It's only a matter of "when" and nature is endlessly patient.

So, why don't we still have dinosaurs?

> "Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth"

If being "earthlike" was enough, this planet would continually be spawning life, as it originally formed. Those "respawns" would then start their own path of evolution. So as well as having us, the result of billions of years of evolution from the first time that life appeared, there would also be forms of plants, animals and all the rest that are the product of evolution from the second time that life started on Earth. And from the third, fourth, the seventy-seventh, the 2,916'th and so on.

But we don't. We only have a single thread of evolution that seems to go back to the start.

So it would seem that being "earthlike" is not a good idea for a planet if it wants to start producing life. It is only a hospitable environment for once life has got past the initial stages. After that, being earthlike is not a set of conditions that is suitable for starting evolution.

The conclusion would be that a planet only has one shot at starting to give rise to life-forms. Maybe once they get to the stage of converting methane, CO2 and ammonia into an environment rich in water and oxygen, they have past the point of spontaneously allowing life to form. If whatever life had developed, then died out, it would explain why we don't see other planets' TV.

The trick wouldn't be starting life, but in having the remarkable set of coincidences, luck, and starting conditions to allow life to avoid all the extinction possibilities in the billions of years after it forms, to eventually give rise to intelligence. Or us!

Re: So, why don't we still have dinosaurs?

there would also be forms of plants, animals and all the rest that are the product of evolution from the second time that life started on Earth. And from the third, fourth, the seventy-seventh, the 2,916'th and so on.

As humans, we have told ourselves the comfortable story of a single thread of evolution, but actually, if they are all based on the same chemicals, then we have no way of telling whether any of what we know of the fossil record and current species are from a first or subsequent attempt at life.

Re: So, why don't we still have dinosaurs?

There's no reason why new life isn't making a new start every day but unless it is sufficiently isolated to evolve a little and develop defence mechanisms, it won't survive for long.To develop defence mechanisms will also require something to predate or compete with it, that takes time so one of our pre-existing and hungry organisms will likely find it before is gets far enough.

Expecting alternative routes for life forming at a later stage in evolution is for the reasons mentioned above, unlikely.

Re: So, why don't we still have dinosaurs?

Everything alive on Earth today shares the same basic molecular machinery, implying a common ancestor. But yes, any of the previous mass extinctions could have been a full stop for some completely different lineage. Interesting thought. Dirty keyboard icon in case a new, more effective, ribosome has just evolved on it thus marking humanity's doom.

Re: So, why don't we still have dinosaurs?

"we have no way of telling whether any of what we know of the fossil record and current species are from a first or subsequent attempt at life."

There's quite a lot about life that could be different but isn't. The set of amino acids in proteins is one and the coding between nucleic acids and amino acids is another. Given 4 types of nucleotide one base pair is worth 2 bits of information so the 3 base pair codon represents 6 bits which is one one hand the minimum but on the other contains many redundancies. A smaller set of amino acids could result in a much more efficient 2 base pair codon and we might expect to see that if there were parallel life chains. Our genetic code is highly conserved, even between such different organisms as animals and plants; we don't see other, equally well conserved, genetic codes amongst the rest of nature. It's possible, of course, that any alternative starts could have been out-competed or simply eaten but, knowing the way life forms survive by interdependence, it seems likely that, had they existed, at least some of them would have been readily recognisable parts of the Earth's ecosystem.

Re: So, why don't we still have dinosaurs?

The code seems very redundant but the code table as it is gives certain very specific structural features which make (at least) recombination easier for certain specific sequences. In modern organisms this minor advantage is unimportant but in simpler beasts it may have been decisive in bootstrapping some of the complex but vital machinery such as ribosomes and recombinases. https://doi.org/10.1017/S0033583517000130

Re: So, why don't we still have dinosaurs?

"So as well as having us, the result of billions of years of evolution from the first time that life appeared, there would also be forms of plants, animals and all the rest that are the product of evolution from the second time that life started on Earth. And from the third, fourth, the seventy-seventh, the 2,916'th and so on."

Modern life has enzymes that make DNA replication fast. Early life did not. Nip back in your TARDIS and bring some early life here and it will get eaten before it can reproduce. Perhaps life did start multiple times in Earth's distant past but it cannot do so again while every habitable environment on the planet is infested with organisms selected by millions of years of evolution to be efficient at exploiting their environment.